System which automatically disables or switches off a cellphone

ABSTRACT

This invention relates to a system for disabling a cellphone in the presence of certain conditions, and for switching it off in the presence of some other conditions, while allowing its use in the normal fashion in the absence of these two sets of conditions. Thus, this system regulates cellphone use in accordance with specified restrictions in specific locations, and allows its normal functioning when these restrictions are not required. Specifically, a first condition is an attempt to operate a cellphone by the driver of a vehicle having its ignition on and/or moving above a certain speed. In such a condition the system would automatically disable the OK switch of a cellphone and may also perform the CALL END function. In the second condition the system automatically switches off any cellphone in the ON condition being carried on the person of an individual occupying a seat in an aircraft, or a committee room, or any other such location where such a restriction is envisaged. The system also makes a provision for automatic sequential dialing of a specified set of numbers like the police, medical services etc. during an emergency by allowing overriding any regulatory restriction. In addition, this invention also relates to control circuits provided in said system for preventing tampering with or bypassing the system by cellphone users.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a device which automatically disables orswitches off a cellphone when first or second conditions arerespectively present and automatically enables the cellphone when saidconditions no longer exist. The first condition is an attempt to operatea cellphone by the driver of a vehicle when its ignition is on or it ismoving above a certain speed. The second condition is when a personoccupying a seat in various locations such as in an aircraft orauditorium endeavors to use the cellphone.

2. Description of Related Art

Reference is made to the first condition, namely an attempt to use acellphone by the driver of a vehicle having its ignition on and/ormoving above a certain speed. When a call is received, the user picks upthe cellphone, looks at the number of the caller on its display panel,and switches on the OK switch of the cellphone in order to receive thecall. In a likewise manner, when the user intends to make a call, itbecomes necessary for him to press the number buttons followed by the OKswitch on the front panel of the cellphone. In both instances, and whensuch an operation is carried out while the user is driving a vehicle,his attention is diverted from the road and traffic condition. Such adistraction is enhanced when he engages into an ensuing conversationwhile driving. In fact, several reports reflect a very strongassociation between traffic accidents and cellphone use by vehicledrivers. Such a danger would also exist, with the provision offacilities like SMS, Multimedia and Internet Access, and Bluetooth®technologies being incorporated in newer generations of cellphones.Thus, several local governments have prohibited the use of cellphone byindividuals while driving a vehicle. The ensuing danger of use of acellphone while driving is recognized in all major countries and similarprohibitions are envisaged. However, even in instances where suchprohibition does exist, people tend to violate the rule and continue touse cellphones while driving vehicles, and enforcing the law becomesnext to impossible.

Hands free cellphones are known in the art in order to obviate to someextent the danger of possible accidents while driving. However, even theuse of such hands free cellphones does not ensure complete safety sincethe driver still has to operate the OK and CALL END switches of thecellphone upon receiving the call and completion of the conversationrespectively, and concentration on conversation can distract thedriver's attention, and is known to significantly impair the reactiontime of a driver. Thus the use of hands free cellphones also is notallowed in several cases. Even if the use of hands free cellphones werepermitted, the proposed system would serve a vital function by blockingthe use of a cellphone in the normal mode by vehicle drivers withoutemploying the hands free kit.

The second condition refers to the situation when a cellphone in the onstate is carried on the person of an individual occupying a seat inlocations such as conference rooms, seminar halls, theaters, or aircraftwhere cellphone use is to be prohibited.

In the past, several systems have been proposed for regulating cellphone use in different locations and situations. The following fourdocuments are relevant to this connection, and it is in order to outlinea brief description of these techniques and their limitations at thispoint.

JP 11 168767 A (NEC CORPORATION) “D1”: This system has been developedwith a view to make communication through a wireless phone system in amoving vehicle impossible. The system incorporates a unit that generatesa logic hi or lo signal to denote either the vehicle ignition being onor off or, alternatively, another unit that generates a logic hi or lowhen the vehicle speed is high or low. The vehicle condition issubsequently transmitted to the mobile phone via radio waves and itsoperating mode is controlled as desired. Another alternative mode oftransmitting the vehicle condition to the cell phone through infraredsignals is also described.

The system has several limitations. Firstly, it makes no provision tocontrol cellphone use in locations other than a vehicle. Secondly, ifthe infrared mode is employed then an unscrupulous individual can easilyblock transmission of the blocking command and the operation of thesystem can be severely compromised. It is difficult to confine the areaof influence of radio waves—the other alternative proposed in thisdocument—to just the space occupied by the driver and, therefore, thesystem is likely to block the mobile phones of the other passengers aswell. The system also makes no provision for making emergency calls froma vehicle in motion by overriding the stipulated restriction.

JP 11 285070 A (KOKUSAI DENKI KK) “D2”: The system described in thisdocument also aims at restricting use of mobile phones in movingvehicles with a view to prevent traffic accidents. The system proposesto incorporate in the cell phone a pick up for the vehicle ignitionnoise. This noise signal is processed through a wave-shaping unit, andthe resulting signal is converted into a voltage signal by afrequency/voltage converter to arrive at the engine rpm. In order toeliminate the interference of the ignition noise signals from othervehicles on the highway, the system also incorporates a means ofdetecting the particular vehicle moving through the electromagneticfield of the communication system and, after comparison with a referencespeed to be set up in the mobile phone, arrives at the condition of theparticular vehicle as either running or stopped. The system alsorequires the driver to select a special “DRIVE KEY” for its activation.When the driver selects the DRIVE KEY and the system detects the vehiclein the running condition, the system locks the keyboard of the mobilephone and also sends a message to the caller that the called person isdriving a vehicle.

This system also suffers from several limitations. Firstly, the means ofestablishing the vehicle condition running or stopped is verycomplicated. Because of the range within which the proposed system inthe mobile phone would pick up the engine ignition noise is fairlyextensive, it would be picked up by the mobile phones of the otherpassengers as well. The DRIVE KEY has been incorporated to enablepersons other than the vehicle driver to use their cell phones. But adriver can also misuse this provision since by not using this particularkey the entire system can be bypassed. The provision to set the speedlimit below which the system permits normal mode of communication canalso be misused by setting a relatively higher speed up to which thevehicle driver can use the mobile phone in the normal mode. There seemsto be no provision for regulating cell phone use in locations other thanin a moving vehicle.

EP 1 035 746 A1 (SONY INTERNATIONAL (EUROPE) GMBH) “D3”: This documentdescribes a system for protecting a predetermined area within which acell phone has to be regulated in a prescribed manner. For this, amobile station transmits a protection signal that is recognized by anycellphone within the area and the cellphone is made to operate in aparticular mode characterized by the signal. The cell phone is restoredto its original mode if it is carried outside that area or if a certainprescribed time elapses after the prohibiting signal is received by it.There is a provision for several modes. In some sensitive areas, thehigh frequency portion of the cell phone may be switched off to avoidthe possibility of interference with other sensitive equipment, while,in other areas, it may be put in a silent mode and, in some cases, thesuppressed output may even be replaced by a visual or non-audibleoutput. The mobile base station has a unit to generate the protectionsignal, which is modulated and radiated to cover the desired area. Themobile phones have to incorporate a protection signal detection sectionand a means to change the mode of its operation. The document covers alarge number of alternative wireless systems categorized in terms of themodulation techniques used, as well as different types, of signalsemployed ranging from broadcast and pager systems, optical/infraredsystems, and acoustic/ultrasonic systems, and discusses their relativemerits and limitations. The preferred system is based on Bluetooth®operating at 2.4 GHz.

While the system has several features that are advantageous in specificapplications like blocking all cell phones with a desired area, it isnot practicable to employ it for blocking cell phone use by vehicledrivers, since the system would block not only the cell phones ofdrivers as well as passengers of vehicles in the zone covered but wouldalso block cell phone use by occupants of offices and residentialbuildings within the covered area. It would also not be practicable toincorporate in a single mobile phone the various types of protectiondetection signals described in the document, and only one or two ofthese say the infrared and the Bluetooth® may be used. As discussedearlier, the infrared can be blocked and the mobile phone can be used,thus bypassing the regulation. Even if a low power jamming stationemploying Bluetooth® were to be incorporated within a vehicle, it wouldpossibly cover the entire vehicle, thus preventing use of a mobile phoneeven by the other passengers. There is also some concern about thehealth-related considerations due to continued exposure to the 2.4 GHzsignal used for Bluetooth®.

EP 0 880 296 A1 (NEC CORPORATION) “D4”: This document describes atransmission restricting system comprising a radio communicationterminal equipment and a transmission restricting device applicable to aspecific area, as well as for drivers of vehicles in motion. The systemis based on the generation and transmission of a command code includedin a magnetic field pattern at the entrance or exit of an area tocommand the transmission interruption to a radio communication terminalequipment, as well as that of another command code included in amagnetic field pattern to command the releasing of the transmissioninterruption to the radio communication terminal equipment also disposedat the entrance or exit of that area. The radio communication terminalequipment comprises means of detecting the magnetic field patterns andinterpreting it for interrupting or releasing radio transmission to itas per command. Any radio communication terminal equipment being carriedin the prohibited area detects the magnetic field pattern of thetransmission interruption controller and interprets the command code toprohibit communication within the area. When the radio communicationterminal equipment is being carried out of the prohibited area, itdetects the magnetic field pattern of the transmission interruptionrelease and interprets the command code to enable communication in anormal mode outside that area. For regulating use of a radiocommunication terminal equipment by the driver of a vehicle being drivenabove a certain speed, the magnetic field pattern of the transmissioninterruption controller is set up in the area of the seat of the driverand, thus, the radio communication terminal equipment cannot be used bythe driver of a vehicle under these conditions. At the same time, themagnetic field pattern of the transmission interruption releaser is setup around the remaining seats in the vehicle, enabling the navigator andother passengers of the vehicle to use the radio communication terminalequipment under the same conditions.

The most attractive feature of this system is obviating the need forcontinuous transmission of the transmission interruption signal insensitive areas, like hospitals. But while the system is positivelydriver specific in blocking radio communication in a moving vehicleallowing the other passengers to talk, it exposes the driver as well asthe other passengers to the magnetic fields of the transmissioninterruption controller and the transmission interruption releasercontinuously all through the duration of a journey. This is undesirablefrom the point of view of health of the occupants of vehicles. Thesystem is also a very complex way of realizing a vehicle driver specificsystem for blocking cell phone use, while enabling the other passengersto use cell phones in a moving vehicle. The system would also besusceptible to malfunction due to distortion in the magnetic fieldpatterns if any object having ferromagnetic material in it is kept inthe vicinity of the poles of electromagnets installed for setting up ofthe desired pattern of magnetic field.

The four documents cited in the Search Report and in the PCT ExaminationReport have been reviewed in the foregoing section. Some limitations ofthese have also been briefly outlined. The jamming system of D3prohibits cell phone use in a specified area by making use of highfrequency signals that are considered to be a health hazard and cannotbe employed for blocking cell phone use by drivers of vehicles in motionwithout also blocking use of cell phones of every other user in the areafalling with the range of the transmitter of the blocking signal. Theother three systems also make use of radio transmission for blockingcell phone use in vehicles. Since radio transmission is difficult to beconfined to a small area, the systems described in the cited documentsare inherently not capable of being vehicle driver specific. In fact,the system described in D4 attempts to solve this problem by resortingto the artifice of creating a specific magnetic field pattern around theseat of the driver for setting up a transmission interruption space, andanother distinct field pattern to set up a transmission interruptionrelease space around the seats of the other occupants of the vehicle.

SUMMARY OF THE INVENTION

The present invention proposes to solve these problems by firstly makinguse of low-frequency signals for communicating the nature of regulationdesired and, secondly, by making use of electrical signals rather thanelectromagnetic or radio waves and, thirdly—and most importantly—throughuse of capacitive couplings for transmission of the signal to command achange in the status of the cell phone. For example, the signalcharacterizing the use of a cell phone by a vehicle driver in accordancewith the state of the vehicle is carried out through two capacitivecouplings—one between a foil embedded in the seat of the vehicle driverand another between the band of the driver and a foil incorporatedwithin the cell phone. The frequency and power level of the signalemployed pose no health hazard and the system is intrinsically driverspecific. The technique for monitoring the state of the vehicle is alsovery simple and direct and is not susceptible to corruption due tointerference from another vehicle on the road, necessitating a veryelaborate method in document D2. Incorporation of a means for automaticdialing of a set of numbers during an emergency by overriding anyregulatory stipulation is another novel feature of the proposed systemmeeting the concern expressed by a cross section of users and lawmakers.The regulation provided by the proposed system is also automatic anddoes not depend on the user being required to use a DRIVE KEY orselecting a particular speed up to which the mobile phone be used by adriver in a moving vehicle, as stipulated in D2.

Since the proposed system makes use of a signal of low frequency in aband far removed from those employed in documents D1 to D4, the type ofsignal generator for communicating a condition to the cell phone, or themeans to detect and interpret the transmitted signal in the cell phone,as well as the technique for controlling the mode of its usage in theproposed system are very different from the systems described in thefour documents cited in the Search Report and the Examiner's Report.Sections [0042] to [0052] of D3 attempt to cover the entire range ofsignal transmission techniques. The use of the capacitive coupling modeof communicating regulatory conditions to a cell phone has not beenemployed anywhere so far, and constitutes a major innovative step. Thismode was arrived at after a critical appraisal of the disadvantages andinherent limitations of various alternatives in current use. Choice ofthis mode was guided by the need to develop a system that wouldeliminate health hazards attributed to prolonged exposure tohigh-frequency radiation, and to arrive at a system that is inherentlyvehicle driver specific, leaving the other passengers free to use theircell phones. The extension of this technique for regulating cellphoneuse in other public places, like libraries or theaters, became a naturalcorollary of the proposed system. The fact that these four citeddocuments also attempt to enhance safety of transportation systems byinhibiting cell phone use by drivers of moving vehicles, and that two ofthese also aim at restricting cell phone use in other locations as well,is the only major aspect that the present proposal has in common withthe systems described in these cited documents. In fact, a criticalappraisal would reveal that the system proposed in this document is notonly novel but also offers several advantages:

-   -   1. use of low power low frequency signals posing no health        hazards;    -   2. use of capacitive coupling, making it an inherently vehicle        driver specific system, leaving the other passengers free to use        their cell phones;    -   3. provision to call a set of designated numbers during an        emergency; and    -   4. use of a technology that is economical and is easy to adopt.

An object of this invention is to propose a system for regulatingcellphone use in accordance with stipulated regulatory conditions, thesebeing the disabling of a cellphone used by a driver in a vehicle, andswitching it off in an aircraft or auditorium, etc., hereafterdesignated as the first and second conditions, respectively.

Another object of this invention is to propose a system whichautomatically disables a cellphone when said first conditions is presentand automatically enables the cellphone when said first condition nolonger exists, and automatically switches off the cellphone in thepresence of the second condition.

Another object of this invention is to propose a system capable ofdistinguishing between the first and second conditions and initiatingthe execution of appropriate regulatory processes stipulated in suchlocations, and incorporating control and switching circuits forregulating cellphone use, which are simple in construction.

A still further object of this invention is to propose a system fordisabling a cellphone in the presence of said first condition, andenabling the cellphone upon removal of said conditions, said systemhaving control circuits, which cannot be tampered or bypassed by acellphone user.

Another object of this invention is to propose a system for allowing auser the facility for automatic sequential dialing of a specified set ofnumbers like the police, medical services etc. during an emergency byoverriding any other stipulated regulation on cellphone use.

Another object of this invention is to propose a system that wouldpresent no health hazard to the cellphone users, while enhancing roadand air travel safety as well as minimizing public inconvenience in itsarea of use.

According to this invention there is provided a system for disabling acellphone in the presence of a first condition and enabling saidcellphone upon removal of said condition, and switching off a cellphonein the presence of a second condition comprising:

-   -   i) a signal generating circuit for generating signals        characterizing the presence of a first or a second condition;    -   ii) a signal detection and processing circuit provided within        said cellphone for receiving and processing a signal from said        generating circuit, and identifying the presence or absence of a        particular condition;    -   iii) an OK switch disabling circuit connected to said signal        detection and processing circuit, said OK switch disabling        circuit connected to the OK switch of the cellphone and        disabling it in the presence of a signal corresponding to the        first condition at the input to the signal detection and        processing circuit;    -   iv) a link and control circuit connected to said OK switch        disabling circuit;    -   v) a call end circuit connected to said link and control circuit        and also connected to the call end switch of the cellphone, and        adapted to perform its function in the presence of a signal        corresponding to the first condition at the input of the signal        detection and processing circuit, and when said OK switch        disabling circuit is disabled.    -   vi) said link and control circuit also connected to the signal        detection and processing circuit and adapted to initiate the        function of the call end circuit in the presence of said first        condition.    -   vii) A circuit to perform the switching off function of the        cellphone and for disabling its on function in the presence of a        signal corresponding to the said second condition at the input        to the signal detection and processing circuit.    -   viii) An emergency switch for enabling the cellphone by        overriding any stipulated regulatory restriction on cellphone        use.

As stated earlier, in this context the first condition relates to anattempt to use a cellphone by the driver of a vehicle having itsignition on and/or moving above a certain speed; while the secondcondition refers to a cellphone in the on state being carried on theperson of an individual occupying a seat in aircraft or auditoria etc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a basic circuit according to the presentinvention;

FIG. 2 shows the block diagram of a Signal Generating and DetectingCircuit provided in the circuit of FIG. 1;

FIG. 3 shows in detail the circuit of FIG. 1;

FIG. 4 shows a control circuit for the power supply to the signalgenerator of FIGS. 1 to 3;

FIG. 5 shows a block diagram of the basic circuit of FIG. 1 inconjunction with certain additional circuits for a switching offoperation for the second condition;

FIGS. 6( a) and 6(b) show various embodiments of Control Circuits forthe Signal Generator;

FIG. 7 shows details of a circuit for regulating a cellphone inaccordance with all stipulated regulatory conditions according to thepresent invention; and

FIG. 8 shows a block diagram of an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the block diagram depicts a Signal Generating UnitI comprising a Signal Generating and Transmitter Circuit Ig that may bepositioned either below the driver's seat or inside the dashboard of thevehicle. The Signal Generating Circuit Ig is linked to a conducting foilF1, enclosed inside the seat of the driver, and forming one part of afirst capacitive coupling CC1 in a manner shown in FIG. 2. Anotherconducting foil F2 provided in the cellphone constitutes a part of thesecond capacitive coupling CC2, and links circuit Ig to a signaldetection and processing circuit II through the terminal T1. The SignalGenerating Circuit Ig is adapted to be connected to the power sourcethrough the Control Circuits of FIG. 4 or 6 a, and would remain in theswitched on condition as long as the ignition of the vehicle remains onand/or it is moving above a certain speed, and thus would signal thepresence of the first condition.

The Signal Generator Circuit Ig is connected to the Signal ProcessingCircuit II located inside the cellphone through the first capacitivecoupling CC1 which is completed whenever the driver's seat is occupied,and a second capacitive coupling CC2 which is completed whenever thecellphone is held by a person occupying the driver's seat. In such aninstance, a disabling signal corresponding to the first condition is fedto Signal Detection and Processing Circuit II and an appropriate commandsignal is communicated to an OK Switch Disabling Circuit III. The Linkand Control Circuit IV is connected to circuits in II, III, and V, anddepending upon the status of signals controls the operation of a CallEnd Circuit V as shown in FIGS. 1 and 3.

In a vehicle, the Signal Generating Unit I generates the characterizingsignal for detecting the condition of the presence or absence of aperson occupying the driver's seat, the on or off status of the ignitionswitch of the vehicle, and/or its state of motion for identifying thefirst condition. It will be apparent that when the driver is present inthe seat of a vehicle and its ignition is on and/or if it is movingabove a certain speed, a signal is generated to disable a cellphone CL,which is the first condition, and whereby the driver cannot utilize thecellphone during the aforesaid first condition. However, for anypassenger of the vehicle not occupying the driver's seat, the cellphonewould remain in an enabled condition.

Referring to FIGS. 2 and 3, a conducting foil F2 provided inside thecellphone is connected to the cellphone antenna ANT through a resistorR15. One end of resistor R15 is connected to the ground of the cellphoneCL while the other end is connected through input terminal T1 to theinverting input of an operational amplifier OP-AMP-2 such as IC2 througha diode D1 and a resistance R2 of the Signal Detecting and ProcessingCircuit II. Another input to OP-AMP-2 comes from the output of a furtheroperational amplifier OP-AMP-1 such as IC1 through a resistance R7. Theinput to OP-AMP-1 is from a potential divider R3 and R4 connected to thepositive terminal of the cellphone supply battery. The output ofOP-AMP-2 is fed to a switching circuit, which by way of example may be anpn transistor TR1. Thus, the output of OP-AMP-2 is fed to the base of atransistor TR1 of the OK switch disabling circuit III connected betweenthe ungrounded side of an OK switch S1 of the cellphone and the systemsupply to this end. This is achieved by removing the connection betweenthe OK switch S1 and the system supply point in the cellphone, andinserting the transistor TR1 in series with switch S1. The other end ofthe OK switch S1 is disconnected from the ground, and connected to thenegative input of operational amplifier OP-AMP-4 of call end circuit V.When the signal across the resistor R15 is zero, the output of thepotential divider R3, R4 is so adjusted as to provide a positive inputto the base of TR-1 through biasing resistor R11 and put it in aconducting mode, and therefore calls can be received or made in a normalfashion. In this condition the output of operational amplifier OP-AMP-4would be a negative pulse.

Thus, in the absence of a signal to terminal T1, which will arise in anabsence of the first condition, the output of OP-AMP-1 would be negativeand that of OP-AMP-2 positive and whereby transistor TR-1 would beforward biased. Thus, the switch S1 would function in a normal fashion.Also when switch S1 is closed, transistor TR3 of circuit V will notconduct and switch S2 would also function normally.

However, when a person occupying the driver's seat picks up thecellphone CL, a path is completed through the capacitive couplingbetween his hand and the film F2 inside the cellphone, the resistanceR15, and the capacitance between the antenna and the vehicle body. Thelevel of the signals is adjusted to drive the output of OP-AMP-2 ofcircuit II and consequently the base of transistor TR1 of circuit III toa negative level sufficient to put it in a non-conducting mode, thusblocking the operation of the OK switch S1. Transistor TR2 of controlcircuit IV may be a pnp transistor and has its collector connected tothe negative supply through resistance R13 and its emitter connected tothe emitter of transistor TR1 as shown. The base of transistor TR2 isalso connected to the output of OP-AMP-2 through resistor R12 as shown.Depending on the polarity of the output of OP-AMP-2, either TR1 or TR2would conduct. When the output of OP-AMP-2 becomes negative, transistorTR2 will conduct. If the OK switch is pressed in this condition, theoutput of OP-AMP-4 would become a positive pulse. The output of OP-AMP-4is connected to the base of transistor TR3 through biasing resistor R16.The collector of TR-3 is connected to the ungrounded terminal of theCall End switch S2, and its emitter is connected to the ground. In thiscondition, when the driver puts the OK switch S1 of the cellphone on,the positive pulse to the base of TR3 would switch it on, thusautomatically performing the call end operation, and would thus preventthe driver from receiving or making a call. In order to make or receivea call it would then be necessary for the driver to switch off theignition and bring the vehicle to a halt. In this situation the outputof OP-AMP-2 and the input to the base of TR1 would again becomepositive, and the OK switch S1 would become functional, thus restoringthe normal operation of the cellphone.

If a passenger other than the driver puts the OK switch on, and handsover the cellphone to the driver, the output of OP-AMP-2 would becomenegative, driving the base of TR-2 negative. This would cause capacitorC3 to discharge through diode D2 and resistor R17 to the negative inputterminal of OP-AMP-4. As a consequence, a positive pulse would appear atthe output of OP-AMP-4, and perform the call end function. Thus thedriver would not be able to bypass the system under any condition

The output of OP-AMP-2 is also connected to the input of OP-AMP-3 asshown in FIG. 3, for generating a control signal for keeping the signalgenerator in an off state and the cellphone in a disabled state if thecellphone is connected to the oscillator socket by a 3 core cable. Onecore connects the ground of the cellphone to that of the signalgenerator, while a core connected to the battery terminal could serve adual purpose of charging the cellphone battery as well as providing anauxiliary input to OP-AMP-2 (through the resistor R1) for disabling theOK switch S1 of the cellphone, while the oscillator OS remains switchedoff by means of a control signal obtained from the output of OP-AMP-3and transmitted to a control switch for putting off the oscillator viathe third core of the cable as shown in FIGS. 2 and 3. If this chord isdisconnected, the oscillator would be automatically switched on, and theOK switch would remain disabled for the driver as long as the ignitionof the vehicle is on and/or it is moving above a certain speed.

Reference is now made to FIG. 5 which shows a modified block diagram ofbasic circuit of FIG. 1 through a modification of the signal detectionand processing circuit II, and the incorporation of an additionalfunctional circuit of block VI, and additional Control and SwitchingCircuits VII and VIII in the Signal Generating Unit I.

In the Signal Generating Unit I, the first Control and Switching CircuitVII connects the Signal Generator Circuit Ig to the power source, andthe Second Control and Switching Circuit VIII provides for disabling thesignal generator on receiving a command through terminal C from thecellphone, and enabling/disabling of any other auxiliary equipmentand/or initiating an alarm signal indicating any tempering with thesystem.

It would be apparent that instead of circuit VI, other additionalcircuits may be added to the basic circuits II to V of FIG. 5, dependingupon any additional functional requirements for the system of FIG. 1.Alternatively, circuit VI may also be present along with otheradditional circuits.

The control and switching circuit VII of FIG. 6( a) shows the modifiedversion of the circuit of FIG. 4 for connecting the signal generator tothe power source of a vehicle. A potential divider PI is connected tothe vehicle battery output through a pressure actuated switch S6. Theoscillator unit OS receives its power from potential divider P1 througha transistor Q8, but all other ICs in the circuit receive their powersupply from the potential divider PI directly as shown in phantom lines.The base of transistor Q8 is connected to the output of a two-inputlogic gate OR4 through a resistor R45 and diode D21. One input of gateOR4 is connected to the output of a taco-generator TG, while the otherinput is the output of potential divider P2. Thus, as long as the seatof the driver is occupied, and either the vehicle's ignition remains onor it is moving above a specified speed, circuit VII ensures that theoscillator OS would receive its power input, and a signal characterizingthe first condition would be communicated to a cellphone held by thedriver of a vehicle in this state.

FIG. 6( a) also incorporates circuit to for ensuring that the proposedsystem for cellphone blocking in a vehicle cannot be bypassed. Thenormally closed contacts NC of relay RL1 can be inserted in theelectrical path between the ignition switch output IGN and the engineENG. The relay coil RL1C of the relay is connected between the ignitionswitch output IGN and the ground through a transistor Q9 and a resistor44 connected in series. FIG. 6( a) also incorporates features fordiscouraging any attempt to tamper with the system. The positive inputof an operational amplifier OPAMP 8, connected as a voltage follower, isconnected to the seat foil through a diode D19 and a resistor R40connected in series. A control input obtained from the cellphone mayfeed the positive input of amplifier OPAMP 9 connected as a voltagefollower. The outputs of OPAMP 8 and OPAMP 9 form the two inputs to thelogic gate NOR3. The output of NOR3 is connected to the base oftransistor Q9 through a series combination of a resistor R43 and a diodeD20. The output of amplifier OPAMP 9 is also connected to the ON/OFFcontrol port COP of the oscillator OS.

Thus, as long as the driver's seat is occupied and the vehicle eitherhas its ignition on or is moving above a specified speed, the oscillatorOS remains on, and the signal from the seat foil F1 to operationalamplifier OPAMP 8 would keep the output of gate NOR3 low. Thus the relaycoil RL1C would not be energized, and the engine would continue toreceive its normal ignition input. This situation would remain unchangedif a command were received from a cellphone connected to the controlinput terminal C. The output of OPAMP 9 would disable the oscillator,and would maintain the output of NOR3 low ensuring normal operation ofthe vehicle. Any attempt to disconnect the seat foil from the oscillatoroutput or the input to OPAMPS 8 and 9 would drive the output of NOR3high and energize the relay coil and thus, cut off the power supply tothe engine of the vehicle, and would switch on an alarm connected to thenormally open contacts NO of relay RL1.

FIG. 6( b) illustrates the connection of a single central oscillator tothe individual conducting foil F1 inside each seat in an aircraft or atheater etc. The oscillator is connected to the seat foil F1 through thenormally open contacts of a pressure-controlled switch S7. When the seatis occupied, the contacts of the pressure-controlled switch S7 areclosed and the oscillator is connected to the seat foil F1. Theoscillator OS is connected to the power source through a central switchS8.

The circuit diagram of FIG. 7 illustrates one circuit that can beincorporated in a cellphone for realizing all regulatory functionsrepresented by blocks Is to VI in FIG. 5, and corresponding parts of thecircuit have also been marked Is to VI. Of these, the circuits in blocksIs, and II to V have functions identical to those of the blocks bearingcorresponding numbers in FIGS. 3 and 5.

The circuit of block II has been modified for distinguishing between thefirst and second conditions for regulating cellphone use, and initiateseither the cellphone disabling function through operation of blocks IIIto V, or initiates the switching off function through the circuits ofblock VI depending upon the polarity of the signal received from thesignal generator. The circuits also incorporate minor modifications forensuring more uniform signal levels for improved reliability ofoperation. For example, in block II the biasing input to OP-AMP-2provided by the output of OP-AMP-1 in FIG. 3 has been replaced by theswitching signal levels of logic gate NOR-1 and OP-AMP-5 in FIG. 7,while the logic gate OR-2 enables the facility for overriding anyregulatory restriction during an emergency. The circuit of block IIIalso has been modified to accommodate multiple system connections to theOK switch of a particular cellphone, and the diodes prevent falseswitching due to stray signals. The circuits in blocks IV and V also canbe seen to be similarly modified versions of the corresponding blocks ofFIG. 3. The circuit of block VII can be seen to be a combination of thecircuits of blocks III to V, but configured to switch off the cellphonein accordance with the regulatory requirement.

In FIG. 7, under normal conditions when no restriction on cellphone useis stipulated, no signal appears at either the antenna input ANT or atthe auxiliary terminal AUX. Consequently, the outputs of OP-AMP-2 andOP-AMP-6 of circuit II would remain low, and the outputs of gates NOR-1and OR-2, and operational amplifier OP-AMP-5, gates NOT-2 and OR-4 ofcircuit II, and operational amplifier OP-AMP-7 of circuit VI wouldbecome high, while the output of gate NOT-1 of circuit II would be low.In this condition transistors Q1 and Q5 of circuit III, and transistorQ6 of circuit VI would be forward biased, while transistor Q2 of circuitIV would be reverse biased. Therefore, the OK switch S1 of circuit IIIwould remain in an enabled condition, and the CPU of the cellphone wouldremain energized through the switching transistor Q6 of circuit VI.Also, under these conditions, signal levels at the output of operationalamplifier OP-AMP-5 and gate NOT-1 of circuit II, and operationalamplifier OP-AMP-7 of circuit VI would remain unchanged, and thereforeOP-AMP-4 of circuit V and OP-AMP-8 of circuit VI would not receive anypulse inputs, and the outputs of gates OR3 of circuit V and OR5 ofcircuit VI would remain low resulting in blocking transistors Q3 ofcircuit V and Q7 of circuit VI. Hence, the OK, CALL END, and ON/OFFswitches of the cellphone would continue to operate in a normal fashionand the cellphone can be used without any restriction.

However, when the driver of a vehicle having its ignition on and/ormoving above a certain speed holds the cellphone, a signal of positivepolarity would appear at the terminal ANT of circuit Is. Since thissignal would be blocked by the diode D12 of circuit II, the CPU of thecellphone would continue to remain energized through the forward biasedtransistor Q6 of circuit VI, and the ON/OFF switch S3 would also operatein the normal manner. But the output of operational amplifier OP-AMP-2would become high, thus driving the outputs of gates NOR1 and OR2, andoperational amplifier OP-AMP-5 to a low value while the output of NOT1would become high. Therefore, transistors Q1 and Q5 of circuit III willbecome reverse biased, and the OK switch will be disabled. If an attemptis made to press the OK switch in this condition, the emitter oftransistor Q2 of circuit IV will be grounded resulting in a negativepulse current due to the discharge of capacitor C4 (initially chargedthrough resistor R13, diode D10, and resistor R27 of circuit IV) to flowthrough diode Dol 1 and resistor R28 to the negative input of OP-AMP-4of circuit V. This would drive the output of gate OR3 to be high leadingto conduction of transistor Q3 of circuit V, and thus automaticallyperforming the CALL END function. If a passenger other than a driverpresses the OK switch S1 and hands over the cellphone to the driver, theoutput of operational amplifier OP-AMP-5 of circuit II would change fromhigh to low causing a negative pulse current due to the discharge ofcapacitor C3 of circuit IV (already charged through diode D7 andresistor R18) to flow through diode D2 and resistor R17 of circuit IV tothe negative input of operational amplifier OP-AMP-4 of circuit V. Thiswould drive the output of gate OR3 to be high leading to conduction oftransistor Q3, thus automatically performing the CALL END function.Since the OK switch remains disabled all through this condition, thedriver will also not be able to call any number. Thus the proposedsystem comprehensively blocks cellphone use by the driver of a vehicleunder the first condition.

In the second condition, the signal received at the terminal ANT wouldbe negative, and would be blocked by diode D1 of circuit II, but wouldbe transmitted to the negative input of operational amplifier OP-AMP-6of circuit II through diode D12 and resistor R30, driving its outputhigh, and the outputs of gates NOT2 and OR4 of circuit II, andoperational amplifier OP-AMP-7 of circuit VI low. This would drive anegative pulse current due to the discharge of capacitor C7 (alreadycharged through diode D14 and resistor R35 of circuit VI) to flowthrough diode D15 and resistor R36 to the negative input of operationalamplifier OP-AMP-8 of circuit VI. This would drive the output of gateOR5 to be high leading to conduction of transistor Q7 of circuit VI, andthus automatically performing the switching OFF function of thecellphone. Furthermore, in this condition the low level of the output ofoperational amplifier OP-AMP-7 would keep transistor Q6 of circuit VIreverse biased and thus preclude energizing the CPU of the cellphone.Thus, all functional requirements on regulating cellphone use are met bythe proposed system.

However, in case of an emergency, a secure switch S4 of circuit II canbe switched on, feeding inputs to gates OR2 and OR4 driving theiroutputs high, thus ensuring normal operation of the cellphoneirrespective of any other condition.

Though the circuit shown in FIG. 7 describes a particular circuit forexecuting the various functions envisaged for the proposed device toregulate cellphone use, it would be apparent that any other circuitcomprising a combination of analog, and logic circuit elements alongwith micro-controllers may be employed to achieve these functions asillustrated through the evolution of the circuits from FIG. 4 to FIG. 6,and from FIG. 3 to FIG. 7, as well as that of the block diagram of FIG.5 to the block diagram of FIG. 8.

The block diagram of FIG. 8 illustrates an embodiment of a practicalversion of a Signal Generating Unit comprising the signal generator Igand its associated control and switching circuits VII, and VIII. Themicro-controller IX is programmed to generate distinct binary signalscharacterizing the stipulated regulatory regime corresponding to thefirst or the second condition. The block diagram of FIG. 8 alsoillustrates an embodiment of a practical version of a circuit to beincorporated in a cellphone and comprises the Signal Detection CircuitIs and a Signal Processing Circuit II similar to the circuit II of FIG.7. The micro-controller X would detect the nature of the binarysignature, and initiate an appropriate regulatory process through itsoutput 20 terminals, said micro-controller X being present in a normalcellphone, or additionally the output of circuit II would be connectedto the micro-controller X through an additional micro-processor (notshown).

The frequency and power level of the signal used in the proposed systemis in a band that is known to cause no health hazard to human beings.However, if the driver of a vehicle desires not to expose himself evento this, he has an option to connect the cellphone to a socket on thesignal generator unit through a chord. This would bring a positivesignal from the terminal marked AUX in FIG. 6( a) to the terminal AUX inFIG. 7, and also connect the ground of the cellphone to the ground ofthe signal generator. This would drive the output of gates NOR1 and OR2,and operational amplifier OP-AMP-5 low, and maintain the cellphone in adisabled state. The chord will communicate a signal from the output ofgate NOR2 of circuit II to the terminal C on the console of SignalGenerating Unit, and would keep its oscillator Ig in an off statethrough its control port COP as long as this chord remains connected. Ifthis connection is broken, the oscillator would be automaticallyswitched on, and the OK switch would remain disabled for the driver aslong as the ignition of the vehicle remains on.

1. A device for disabling cellphone use in the presence of a first or asecond condition, and enabling its normal functioning upon removal ofsaid conditions, said first condition being that of a signal generatedfrom a vehicle in motion, said second condition being that of a signalgenerated from a restricted area, said device comprising: (i) a signalgenerating circuit adapted to generate a polarity specific signalcorresponding to said first or second condition; (ii) a signal detectionand processing circuit provided within said cellphone for receiving andprocessing the signal from said signal generating circuit, said signaldetection and processing circuit coupled to the signal generatingcircuit through a first capacitive coupling to the signal detection andprocessing circuit, and a second capacitive coupling provided in thecellphone and linked to the signal detection and processing circuit;(iii) an OK switch disabling circuit connected to said signal detectionand processing circuit, said OK switch disabling circuit connected tothe OK switch of the cellphone and disabling it in the presence of asignal corresponding to said first condition to said signal at an inputto the signal detection and processing circuit; (iv) a link and controlcircuit connected to said OK switch disabling circuit for terminating acall if a cellphone in an operating mode is passed on to a driver byanother passenger in the presence of said first condition as well as tosaid signal detection and processing circuit; (v) a call end circuitconnected to said link and control circuit and also connected to thecall end switch of the cellphone, and adapted to perform its function inthe presence of a signal corresponding to the first condition at theinput of said signal detection and processing circuit, when said OKswitch is also disabled; (vi) said link and control circuit alsoconnected to said signal detection and processing circuit and adapted toinitiate the function of the call end circuit in the presence of saidfirst condition; and (vii) a cellphone switching off circuit, linked tosaid signal detection and processing circuit, for switching off thecellphone and disabling its ON function in the presence of said secondcondition at the input to the signal detection and processing circuit.2. A device as claimed in claim 1 wherein said second coupling comprisesa conducting film disposed within said cellphone and connected to anantenna of said cellphone through a resistance.
 3. A device as claimedin claim 1 wherein said signal detection and processing circuit isconnected to said OK switch disabling circuit, and the call end circuitfor blocking cellphone use by adapted to disable its OK switch andadapted to perform the call end function in the presence of said firstcondition, said call end circuit incorporating a switching circuitconnected across the call end switch of the cellphone.
 4. A device asclaimed in claim 1 wherein said cellphone switching off circuit isconnected to said signal detection and processing circuit, and adaptedto perform the switching off function of the cellphone in the presenceof said second condition.
 5. A device as claimed in claim 1 wherein saidsignal generator is adapted to be connected to a power source through acontrol and switching circuit, and linked to a second control andswitching circuit while configured for generating a signal for saidfirst condition.
 6. A device as claimed in claim 1 wherein a centralsignal generator is adapted to be connected to a power source through amain switch, and connected to individual seat foils through pressureactuated switches when configured for generating a signal indicating thepresence of said second condition.
 7. A device for disabling a cellphonein the presence of a first or a second condition and enabling saidcellphone upon removal of said conditions, comprising a signalgenerating circuit for generating specified binary signaturecharacterizing first or second conditions and connected to a powersource through a first control and switching circuit and a secondcontrol and switching circuit, said signal generating circuitincorporating a micro-controller and linked to a signal detection andprocessing circuit through a first and second capacitive coupling forsignal demodulation for regulating cellphone use through amicro-controller normally provided in a cellphone.
 8. A device asclaimed in claim 1 comprising an emergency switch to allow the dialingof a set of emergency numbers to override said first and secondconditions.